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HelpTest Code B2MC Beta-2-Microglobulin (Beta-2-M), Spinal Fluid
Reporting Name
Beta-2-Microglobulin, CSFUseful For
Evaluation of central nervous system inflammation and B-cell proliferative diseases
Method Name
Nephelometry
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
CSFSpecimen Required
Container/Tube: Sterile vial
Specimen Volume: 1 mL
Collection Instructions: Send spinal fluid from collection vial 1.
Specimen Minimum Volume
0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| CSF | Refrigerated (preferred) | 28 days | |
| Frozen | 28 days | ||
| Ambient | 14 days |
Reject Due To
| Gross hemolysis | OK |
Reference Values
0.70-1.80 mcg/mL
Day(s) Performed
Monday through Friday
CPT Code Information
82232
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| B2MC | Beta-2-Microglobulin, CSF | 1951-3 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| B2MC | Beta-2-Microglobulin, CSF | 1951-3 |
Clinical Information
Beta-2-microglobulin (beta-2-M) is a small membrane protein (11,800 Da) associated with the heavy chains of class I major histocompatibility complex proteins and is, therefore, on the surface of all nucleated cells. The small size allows beta-2-M to pass through the glomerular membrane, but it is almost completely reabsorbed in the proximal tubules.
Increased beta-2-M levels in the cerebrospinal fluid (CSF) have been shown to be of diagnostic use in non-Hodgkin lymphoma with central nervous system involvement. Elevated CSF:serum ratios seen in patients with aseptic meningoencephalitis suggest the possibility of neurologic processes including those associated with HIV infection and acute lymphoblastic leukemia. Beta-2-M measurement in multiple sclerosis seems to be of indeterminate usefulness.
Interpretation
Elevations of cerebrospinal fluid beta-2-microgobulin levels may be seen in a number of diseases including malignancies, autoimmune disease, and neurological disorders.
Cautions
Results determined by assays using different manufacturers or methods may not be comparable.
Method Description
In this Siemens Nephelometer II method, the light scattered onto the antigen-antibody complexes is measured. The intensity of the measured scattered light is proportional to the amount of antigen-antibody complexes in the sample under certain conditions. If the antibody volume is kept constant, the signal behaves proportionally to the antigen volume. A reference curve is generated by a standard with a known antigen content on which the scattered light signals of the samples can be evaluated and calculated as an antigen concentration. Antigen-antibody complexes are formed when a sample containing antigen and the corresponding antiserum are put into a cuvette. A light beam is generated with a light emitting diode, which is transmitted through the cuvette. The light is scattered onto the immuno-complexes that are present. Antigen and antibody are mixed in the initial measurement, but no complex is formed yet. An antigen-antibody complex is formed in the final measurement. The result is calculated by subtracting the value of the final measurement from the initial measurement. The distribution of intensity of the scattered light depends on the ratio of the particle size of the antigen-antibody complexes to the radiated wavelength.(Instruction manual: Siemens Nephelometer II, Siemens, Inc.; Version 3, 2008; Addendum to the Instruction Manual 2.3, 08/2017)